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Conservation of the 17-kilodalton antigen gene within the genus Bartonella.

ABSTRACT: The 17-kDa antigen of Bartonella henselae has previously been shown to elicit a strong humoral immune response in patients with cat scratch disease (CSD) and to be useful in screening human serum samples for CSD. In this study, PCR amplification of genes homologous to the 17-kDa antigen gene of B. henselae was performed using genomic DNAs from several species of Bartonella, including the currently recognized human pathogens. Amplicons of similar size were demonstrated using the following chromosomal DNA templates: B. henselae (two strains), B. quintana (two strains), B. elizabethae, B. clarridgeiae, B. vinsonii subsp. vinsonii, and B. vinsonii subsp. berkhoffii. No evidence of a B. bacilliformis homolog of the 17-kDa antigen gene was obtained using multiple primer pairs. DNA sequencing revealed open reading frames capable of coding for proteins with sizes similar to that of the 17-kDa antigen of B. henselae in all of the amplicons; however, extensive sequence divergence across the genus was noted. Cloning of the amplified products into pUC19 resulted in recombinants that directed synthesis of homologs of the 17-kDa protein. Immunoblot analysis using human sera from CSD cases demonstrated very little cross-reactivity among different species for this protein. In contrast, immunoblots using rabbit serum raised to the recombinant B. henselae antigen showed extensive cross-reactivity with the proteins of other Bartonella species. The data suggest that the use of the 17-kDa antigen as a serologic reagent may allow the development of more specific diagnostic assays. Furthermore, the nucleotide sequences from the various versions of the 17-kDa antigen gene should be useful for rapid identification of Bartonella at the species level.

SUBMITTER: Sweger D

PROVIDER: S-EPMC95857 | biostudies-literature | 2000 Mar

REPOSITORIES: biostudies-literature

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Conservation of the 17-kilodalton antigen gene within the genus Bartonella.

Sweger D D Resto-Ruiz S S Johnson D P DP Schmiederer M M Hawke N N Anderson B B

Clinical and diagnostic laboratory immunology 20000301 2

The 17-kDa antigen of Bartonella henselae has previously been shown to elicit a strong humoral immune response in patients with cat scratch disease (CSD) and to be useful in screening human serum samples for CSD. In this study, PCR amplification of genes homologous to the 17-kDa antigen gene of B. henselae was performed using genomic DNAs from several species of Bartonella, including the currently recognized human pathogens. Amplicons of similar size were demonstrated using the following chromos ...[more]

PMID: 10702501

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Project description:Transcription start sites (TSSs) lying inside annotated genes, on the same or opposite strand, have been observed in diverse bacteria, but the function of these unexpected transcripts is unclear. Here, we use the metal-reducing bacterium Shewanella oneidensis MR-1 and its relatives to study the evolutionary conservation of unexpected TSSs. Using high-resolution tiling microarrays and 5'-end RNA sequencing, we identified 2,531 TSSs in S. oneidensis MR-1, of which 18% were located inside coding sequences (CDSs). Comparative transcriptome analysis with seven additional Shewanella species revealed that the majority (76%) of the TSSs within the upstream regions of annotated genes (gTSSs) were conserved. Thirty percent of the TSSs that were inside genes and on the sense strand (iTSSs) were also conserved. Sequence analysis around these iTSSs showed conserved promoter motifs, suggesting that many iTSS are under purifying selection. Furthermore, conserved iTSSs are enriched for regulatory motifs, suggesting that they are regulated, and they tend to eliminate polar effects, which confirms that they are functional. In contrast, the transcription of antisense TSSs located inside CDSs (aTSSs) was significantly less likely to be conserved (22%). However, aTSSs whose transcription was conserved often have conserved promoter motifs and drive the expression of nearby genes. Overall, our findings demonstrate that some internal TSSs are conserved and drive protein expression despite their unusual locations, but the majority are not conserved and may reflect noisy initiation of transcription rather than a biological function. Importance: The first step of gene expression is the initiation of transcription from promoters, which have been traditionally thought to be located upstream of genes. Recently, studies showed that in diverse bacteria, promoters are often located inside genes. It has not been clear if these unexpected promoters are important to the organism or if they result from transcriptional noise. Here, we identify and examine promoters in eight related bacterial species. Promoters that lie within genes on the sense strand are often conserved as locations and in their sequences. Furthermore, these promoters often affect the bacterium's growth. Thus, many of these unexpected promoters are likely functional. Fewer promoters that lie within genes on the antisense strand are conserved, but the conserved ones seem to drive the expression of nearby genes.

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Dataset Information

Conservation of the 17-kilodalton antigen gene within the genus Bartonella.

Publications

Conservation of the 17-kilodalton antigen gene within the genus Bartonella.

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